Using Satellite Observations with Field Surveys to Monitor Ecosystem Restoration in AlUla, Saudi Arabia

Abstract. AlUla, a historic town located in Northwestern Saudi Arabia, renowned for beautiful landscapes and cultural significance. With the establishment of The Royal Commission for AlUla (RCU) in 2018, remarkable efforts have been made including, establishment of national parks and nature reserves, implementation of grazing control measures, and various planting initiatives. Monitoring of these efforts has been confined to an annual scale and not on a quarterly basis, which would allow for a more detailed, short-term assessment of their impacts. This study aims to provide a quarterly assessment of NDVI-based land cover and anomaly in Sharaan NP and Gharameel NR during the year 2024. A vegetation survey was conducted in the first trimester of 2024 (Jan–Mar), where species biomass, cover, height was collected using the line-transect method. For short-term and long-term analysis images were collected from Landsat (5-9) and Sentenile-2 satellites, Landcover was derived based on NDVI from Sentinel images. While NDVI anomaly was derived from Landsat datasets. The Analysis was conducted on a trimestral basis (Q1: Jan–Mar, Q2: Apr–Jun, Q3: Jul–Sep, Q4: Oct–Dec). Mean NDVI was calculated and compared to historical averages for anomaly calculation. NDVI showed a marked increase compared to previous years (1990–2023). Vegetation cover trimestral variations were driven by seasonal changes. Sharaan NP showed the best vegetation conditions throughout the year compared to Gharameel NR which is likely due to fencing and livestock grazing exclusion. The relationship between vegetation cover and landscape variability is strongly influenced by the capacity for moisture retention in valleys, hills, and sloped terrains, underscoring the need to keep prioritizing and enhancing restoration efforts in these significant landscapes.